BF Goodrich Company/University of Akron Archives

Test pilots in the 1960s showing off the flexibility of the lightweight Mark IV suits.

These marvels are far smaller than the towering rockets and streamlined spacecraft that took men into orbit and to the Moon. Far softer, too. They are the spacesuits that kept the astronauts alive beyond Earth.

Most of the National Air and Space Museum’s collection of about 300 spacesuits is here, laid out five high on steel racks in a climate-controlled room. Each is protected by a sheet of muslin, giving the room the eerie feel of a morgue or the final resting place of members of an odd space cult.

There are Mercury suits like the one worn by Scott Carpenter, the fourth American in space, its iconic reflective coating coming off in spots. There’s the Apollo 11 suit worn by Neil A. Armstrong, looking about as pristine as when he made his first small step on the moon in 1969, thanks to a cleaning job by NASA that, in retrospect, was ill advised because it damaged the materials the suit was made of. Nearby lies Harrison H. Schmitt’s Apollo 17 outfit, still heavily coated in lunar grit.

There are many suits that never made it into space, projects like the EX1-A, which had doughnut-shaped joints that allowed the wearer full limb movement; the AX-5, which looks like a space-age version of the Michelin Man; and the AES, which was covered almost entirely in fabric of woven stainless steel. (It looks fabulous and was fabulously expensive.)

There are accessories, too: lunar booties with the same stainless-steel fabric on top; Manned Orbiting Laboratory gloves with sharkskin palms and sewn-in steel fingernails, so nimble that an astronaut could pick up a dime while wearing them, even when they were pressurized; long johns laced with plastic pipes, to water-cool the wearer; and box after box of headgear, including Mr. Armstrong’s gold-visored external helmet, once thought to have been left on the Moon.

The spacesuits will get their due next spring, in a traveling exhibition of full-size photographs and X-ray images organized by the Smithsonian. (Most of the suits — especially their rubber components, which have become brittle over the decades — are too fragile to be displayed.) Last month, a few of the people who know most about spacesuits gathered at the museum for a panel discussion about the design decisions and trade-offs that went into creating these most personal of space-race artifacts.

“A lot of it is engineering,” Joseph J. Kosmo, a senior project engineer with NASA who has designed spacesuits for nearly 50 years, said in an interview. “But a lot of it is art, too.”

At its most basic, a spacesuit is meant to perform two nearly incompatible functions: protect the astronaut from the harsh environment of space, and allow the wearer to maneuver and work comfortably.

“The emphasis is on trying to develop a very mobile system while pressurized,” said Mr. Kosmo, who in 1961, fresh out of college with a degree in an aeronautical engineering, was asked if he’d be interested in a job described as working on “spacesuits, whatever they are.”

A pressure suit — a rubber bladder and a sealed helmet — allows the astronaut to survive in the vacuum of space. But a bladder is constricting when unpressurized, and when it is inflated movement becomes even more difficult, because moving the joints reduces the volume, increasing the pressure inside.

“When you pressurize it, it’s like working inside of a sausage,” said Dr. Joseph P. Kerwin, an astronaut aboard the Skylab mission in 1973 and the Apollo program “suit guy” — the astronaut who worked most closely with spacesuit engineers — for several years before that. “The whole trick in designing a spacesuit was to make it easier to move the joints inside that inflated balloon.”

So engineers, including Mr. Kosmo, spent years using their knowledge of anatomy, movement and materials to develop better joints.

The doughnut-shaped ones on the EX1-A were a solution — they are hard joints, so the volume of the suit remains constant when movement occurs, and there is no pressure increase.

A more practical solution, however, turned out to be something called a convolute — accordionlike folds in the bladder at the shoulders, knees and other joints. With a system of cables to keep the folds from stretching, convolutes provided a good degree of movement.

The first suits, for the solo Mercury flights from 1961 to 1963, were variations on military high-altitude flight suits and were simpler, said Amanda Young, who spent 15 years organizing the museum’s suit collection before retiring in 2009. (Aside from a few later prototypes, the collection ends with post-Apollo projects like Skylab; shuttle and space station suits are not yet included.)